Most earth drilling systems employ some form of rotary or percussion powered drills. Typically, a drilling machine, such as for forming a hole for an explosive charge, or for anchoring a roof bolt, includes a drill socket for receiving a stem with a drill bit on the distal down hole section thereof. The stem/bit on a rotary drill machine is rotated by a shaft, sometimes called a spinner, mounted on a drill head to form the drill hole. The rotary driving motion of the spinner is usually hydraulically or pneumatically driven.
Various types of drilling systems utilize a drilling fluid in combination with a drilling tool. This drilling fluid may be a liquid such as water or a water-containing liquid. The uses of a drilling fluid may include assisting in removing drill cuttings from a borehole, stabilizing borehole walls to prevent caving, controlling dust produced during the drilling process, and cooling and cleaning the drill bit. Such use of a drilling tool with a drilling fluid may be termed wet-drilling.
As can be seen in FIG. 1, wet-drilling generally involves the introduction of the drilling fluid into a borehole in a surface to be drilled, such as through a channel within the drill bit. As the drilling fluid is introduced into the borehole, the fluid cools the cutting edge of the drill bit and flush away the dust and cuttings within the borehole. The combination of fluid and cuttings is generally forced out of the borehole through an annulus between the drill bit and the borehole. By flushing away the cuttings, the longevity of the drill bit may be extended because the drill bit is not forced to continuously re-cut the cuttings within the borehole. By reducing or eliminating the dust created during the drilling process, the air quality in the mine may be greatly improved.
In the case of overhead drilling, such as in the drilling in the roof of a mine shaft, the amount of drilling fluid used may be increased in comparison to a horizontally drilled borehole. This additional fluid may be necessary to maintain the advantages of wet-drilling, as gravity forces the fluid out of the overhead borehole more quickly than a horizontal borehole. As gravity forces the combination of fluid, dust, and cuttings (i.e. the waste fluid) down the shaft of the drill bit, the spinning of the drill, especially at the drill head, may cause this waste fluid to be rapidly and somewhat violently dispersed in the mine shaft in the area of the drill. This dispersed waste fluid deleteriously accumulates in the mine and makes for unpleasant working conditions.
Accordingly, a need is identified for an apparatus that provides an improvement in wet-drilling overhead boreholes within a mine.